There has been reported a technique in which irregularities are formed on the light takeout surface of a light-emitting semiconductor element in order to heighten the efficiency in light takeout of the light-emitting semiconductor element (see, for example, patent document 1).
However, the processing of a semiconductor surface for forming irregularities thereon necessitates etching by the RIE (reactive ion etching) or ion milling method and this step takes troubles and costs.
Hence, there has been proposed a technique in which an antireflection film comprising a polyimide resin and TiO2 added thereto is formed on the light takeout surface of a light-emitting semiconductor element and irregularities are formed on the surface of the film with a die press to thereby improve the efficiency in light takeout (see, for example, patent document 2).
Patent Document 1: JP 2000-196152 A
Patent Document 2: JP 2003-174191 A
However, since the film comprises a polyimide, the formation of irregularities on the surface of the film with a die press usually necessitates application of a pressure higher than 1 MPa to the light-emitting semiconductor element at 300° C. or higher. There is a possibility that such a high temperature and high pressure might damage the light-emitting semiconductor element.